It is not only spirits who punish the evil, the soul brings itself to judgment: and also it is not right for those who endure for ever to attain everything in a short time: and also, there is need of human virtue. If punishment followed instantly upon sin, men would act justly from fear and have no virtue.
SallustThe soul sins therefore because, while aiming at good, it makes mistakes about the good, because it is not primary essence. And we see many things done by the Gods to prevent it from making mistakes and to heal it when it has made them. Arts and sciences, curses and prayers, sacrifices and initiations, laws and constitutions, judgments and punishments, all came into existence for the sake of preventing souls from sinning; and when they are gone forth from the body, Gods and spirits of purification cleanse them of their sins.
Sallust